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Opthalmology team clears eyes for Dallas Zoo gorilla

Sep 14, 2009

By Russell Rian

As the usual throngs have made their way to see the popular gorilla exhibit at the Dallas Zoo this summer, one of the gorillas has looked back with better eyesight thanks to assistance from UT Southwestern ophthalmologists.

In January, UT Southwestern ophthalmologists and zoo veterinarians conducted a rare cataract removal and replacement lens surgery on 47-year-old Timbo, a western lowland gorilla. That procedure was the result of earlier research by UT Southwestern ophthalmologists conducted to identify commonalities between the eyes of humans and gorillas.

“It’s been gratifying to see Timbo doing so well,” said Dr. R. Wayne Bowman, professor of ophthalmology and part of the team of ophthalmologists and veterinarians who performed the surgery.

Timbo the gorilla received an artificial lens during an operation in January. Dr. Wayne Bowman led a team of ophthalmologists from UT Southwestern and veterinarians from the Dallas Zoo.

Gorillas, like humans, can start losing vision as they get older. At age 47, Timbo has eyes comparable to those of a 65-year-old human. She could see well enough to eat and move about her habitat, but zookeepers were concerned that she might not be able to compete with her two new and much younger companions for her share of the lettuce, bananas and smaller food items that make up their diet.

The eventual diagnosis was cataracts, a clouding of the lens that is readily handled in humans by lens replacement surgery. Surgeons removed the cloudy lens and inserted an artificial lens to restore the near, middle and far distance vision.

Zookeepers noticed improvement within a week of surgery on the first eye, and the second was repaired with equally positive results. Timbo began foraging for smaller items within the habitat, and she seemed to be more aware of things inside the gorilla holding area as well as outside in the habitat.

Such a surgery is extremely rare in gorillas. Researchers found only a few other cases in the scientific literature.

Fortunately, UT Southwestern already had some of the world’s experts on hand. What evolved was a combination effort from the ophthalmology team, the zoo veterinarians and caretakers, and local ophthalmology labs.

Dr. James McCulley, chairman of ophthalmology, and Dr. Nick Hogan, associate professor of ophthalmology, did much of the previous work on normal gorilla ocular anatomy that led surgeons to believe the surgery could be successful.

Dr. McCulley published physiological studies, including one published in the Journal of Zoo and Wildlife Medicine, years earlier, clinically comparing the eyes of gorillas and humans. In that study, researchers examined the eyes of five gorillas from the Dallas Zoo ranging in age from 12 to 48, including Timbo.

“What we found were important similarities between the eyes of the western lowland gorilla and human eyes,” said Dr. McCulley. “These similarities suggested that diagnostics, techniques and equipment for human eye surgery, such as those used for cataract extraction and intraocular lens implantation, could be successfully utilized for gorillas.”

And that’s exactly what came to pass, thanks to the assembled team.

Dr. Wayne Bowman checks on Timbo in the observation bunker at the Dallas Zoo.

“This surgery could not have been done without the help of many individuals who deserve recognition for their time and effort and the great pre-operative and postoperative care Timbo received at the zoo,” said Dr. Bowman, who performed the surgery.

Dr Kamel Itani, professor of ophthalmology, performed the measurements essential to using the correct intraocular lens implant. Dr Yu-Guang He, associate professor of ophthalmology, examined and studied Timbo’s eyes. Dr. John Carmody, assistant instructor of ophthalmology, helped coordinate and assisted with the surgery. Dr. Bowman and Dallas Zoo veterinarians Dr. Tom Alvarado and Dr. Janis Raines took part in the procedure and were also assisted by registered nurse Sue Clouser and Shanann Dixon, outpatient surgery technician.

Alcon Laboratories of Fort Worth and its representatives John Flood and Pat Cavanaugh donated the most advanced instruments available for cataract surgery, along with all the supplies and intraocular lenses. Zeiss Instruments, through its agent Elish Modi, delivered and lent the most advanced surgical microscope made.

Dr. Bowman holds the Irene Wadel and Robert I. Atha Professorship in Ophthalmology.